An inductor is generally used for an oscillating circuit, filter circuit, transformer, matching circuit. Further, according to advanced technology for integration of a semiconductor, the inductor is used for RFIC (Radio Frequency-Integrated Circuit), which is a single semiconductor device having modulation/demodulation circuit for processing high frequency signals, and the inductor is used as a choke coil for power supply IC. Therefore, multiple inductors will be arranged on one electronic circuit.
In that case, since it is preferable to avoid generating magnetic coupling of multiple inductors, the multiple inductors are arranged at a wide interval. Therefore, a large installation space on an electronic circuit for arranging the inductor on an electronic circuit is required.
In order to avoid degradation of circuit characteristic, it is known that a semiconductor integrated circuit utilizes two spiral inductors for differential signals and thereby reduce a leakage of magnetic flux into the outside of the spiral inductors. In the semiconductor integrated circuit, a first spiral inductor turns in the opposite direction to a second spiral inductor. Therefore, if the differential signals flow in the first spiral inductor and the second spiral inductor, for example, if an upward magnetic field in the center section of the first inductor is generated, a downward magnetic field in the center section of the second inductor is generated. In this way, since the generated magnetic fields are directed such that both magnetic fields are enhanced, reactance and Q value of spiral inductors are improved. It is known that Japanese Laid-open Patent Application Publication No. 2006-60029 discusses related technology.
However, in the above mentioned conventional technology, if magnetic field generated by one of the spiral inductors passes through center of the loop of the other of the spiral inductors, the direction of a differential signal flowing in the one of the spiral inductor is limited to improve the Q value, and it is impossible to reduce an influence in other spiral inductor generated by one of the spiral inductors.